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 ''' 2.2. Obtaining Information about the Display, Image Formats, or Screens '''

The Xlib library provides a number of useful macros and corresponding functions that return data from the Display structure. The macros are used for C programming, and their corresponding function equivalents are for other language bindings. This section discusses the: All other members of the Display structure (that is, those for which no macros are defined) are private to Xlib and must not be used. Applications must never directly modify or inspect these private members of the Display structure.
 * Display macros
 * Image format functions and macros
 * Screen information macros

2.2.1. Display Macros 

Applications should not directly modify any part of the Display and Screen structures. The members should be considered read-only, although they may change as the result of other operations on the display.

The following lists the C language macros, their corresponding function equivalents that are for other language bindings, and what data both can return.

Both return a value with all bits set to 1 suitable for use in a plane argument to a procedure.

Both BlackPixel and WhitePixel can be used in implementing a monochrome application. These pixel values are for permanently allocated entries in the default colormap. The actual RGB (red, green, and blue) values are settable on some screens and, in any case, may not actually be black or white. The names are intended to convey the expected relative intensity of the colors.